Fig. 3
From: The identification of carbon dioxide mediated protein post-translational modifications
Characterisation of carbamate trapping on the ε-NH2 group of α-N-acetyl-lysine. a Total ion chromatogram of the carbamate-trapping reaction mixture of α-N-acetyl-lysine with TEO, and m/z profile for species at retention time ~2.6 min. The major products of the trapping reaction are N-acetyl-lysine ethylated on the α-carboxylate group (retention time ~1.7 min), α-N-acetyl-lysine ethylated on the α-carboxylate and ε-NH2 groups (retention time ~2.1 min) and α-N-acetyl-lysine ethylated on the ε-carbamate and the α-carboxylate groups (retention time ~2.6 min). b MS trace demonstrating the increase of one mass unit from 12C (i) with the use of 13C labelled CO2 (ii). c. 1H-NMR spectra comparing ethyloxycarbonyl signals between a chemically synthesised α-N-acetyl-ε-N-ethyloxycarbonyl-lysine and b ethylation products formed during the trapping experiments between α-N-acetyl-lysine, CO2 and TEO (key CH2 signals highlighted in red)
